I know I'm over 5 years too late for this thread however I just wanted to point out for anyone that found this thread in a search etc that the Temperaturregler is not related to the climate control.

The relay/control unit responsible for the climate control is also located beneath the glove box & behind the passenger side "knee Pad" (the carpet covered ducting) along with blower motor/fan but is a black plastic module produced by VDO called the "Klima" Relay.

Despite the seemingly misleading name, the Temperaturreguler is the first generation W126's "Engine Control Brain". Amazingly ingenious in its design, this analogue:electric (not electronic) unit uses the current sent from the sensors that bolt in to the coolant block along with that of the Throttle Position Sensor & TDC sensor to help regulate the engine speed, numerous other airflow/exhaust functions & ignition timing.

So... If you've narrowed your HVAC system issues down to the climate control module then you want to replace or repair the black plastic Klima Relay, not the alloy cased Temperaturreguler.

Hi W126world, welcome to the forum.

The Temperaturreguler, in my original post, is indeed used for HVAC.

Its is also used on:
---W126 diesel models which have no electronic control over anything engine related.
---W123 chassis cars
---R107 chassis cars.

Attached to my post here is a snippet from the new Mercedes-Benz parts catalog (they recently changed over from an older java based program to a full web based one). It shows the part number for the temperature regulator located in the HVAC section (83).

Idle control, on the first gen W126 was handled by a module that looks like this. I've worked on a few.
https://www.ecklersmbzparts.com/assets/ppm/images/size/600x600/sku/P54-228.jpg

Ignition related matters was handled an ignition control module.Originally made by Bosch looking something like this: https://www.**********.com/Images/BigPictures/0025452632-MFG250-2.jpg

I've seen an aftermarket replacement solution by Hueco, its much smaller.
The second gen W126 have the EZL for ignition control.

--Kris